Speed painting (mostly from random photos off flickr) done with India ink and a large brush:
The goal in these is forcing myself to ignore details and look just at the apparent values of the landscape - light and dark areas. The principle is the same of the gesture drawings of animals.
If I sketch landscapes with a pen I tend to draw a huge flat mess like this:
I sketched this in a hort full of plants and visual noise (many small leaves and branches etc.). In such situations I get distracted by details and I don't even think about values, but values are the most important thing to achieve a good composition, so they are also the most important when drawing a landscape from the mind. This was the first painting where I designed the landscape thinking just of values and light/dark areas: